Ashok Panigrahy MD, Presenter: Nothing to Disclose

Marvin Dale Nelson MD, Abstract Co-Author: Nothing to Disclose

Floyd H. Gilles, Abstract Co-Author: Nothing to Disclose

Jane Tavare, Abstract Co-Author: Nothing to Disclose

Stefan Bluml PhD, Abstract Co-Author: Nothing to Disclose

To determine age-dependent and regional-dependent changes of glutamate concentrations in the developing human brain using quantitative in vivo MR spectroscopy (MRS).

552 MR spectra, obtained from 416 subjects, including newborns, infants, children and young adults (post-conceptional age (PCA): 25-1000 wks (19.2 yrs)) with normal MRI report were reviewed. 317 spectra were acquired from the occipital grey matter (GM) and 234 spectra were acquired from parietal white matter (WM). Subjects were enrolled in unrelated research studies or had clinical indications for MRI/MRS. A neonatal head coil was used. The retrospective review of MRS data was approved by the IRB. All MRS studies were carried-out on a 1.5T GE scanner. Fully automated LCModel software (Stephen Provencher Inc., Oakville, Ontario, Canada) was used to process single voxel 1H spectra (PRESS, TE = 35 msec) and to quantify absolute concentrations (in mmol/kg) of N-acetylaspartate (NAA), creatine (Cr), glutamate (Glu), glutamine (Gln). The water signal, corrected for age-dependent changes, was used as an internal concentration reference. Metabolite concentrations were plotted versus PCA and sigmoid functions were used to fit the data.

In WM and GM, glutamate, Cr, and NAA increased rapidly between ≈ 38 – 70 weeks PCA. Glu in WM (3.7±2.0 mmol/kg for PCA < 39 wks) reached a maximum at ≈ 60 weeks PCA (≈10.3) and thereafter decreased moderately to adult levels (8.6±1.1). Cr also demonstrates a similar peak in WM at 55 weeks PCA. In GM, glutamate increased from 4.4±1.5 to 12.9±1.3 and a plateau at early brain development was not observed. Similarly, no plateau was observed for Cr in GM or for NAA in WM and GM. Glutamine remained constant (3.9±1.4 mmol/kg (WM) and 4.9±1.5 (GM)).

Significant age and region dependent changes of glutamate were detected by quantitative MRS, indicating a critical period of glutamate metabolism in the human brain particularly in the parietal white matter.

This study provides baseline “control” information for the in vivo evaluation of excitotoxic glutaminergic mechanisms in perinatal brain injury using quantitative MRS.

Panigrahy, A, Nelson, M, Gilles, F, Tavare, J, Bluml, S, In Vivo Quantitation of Glutamate in the Human Brain with MR Spectroscopy: Age-dependent Changes and Regional Variation.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5010186.html